Systems and methods for electrical energy storage

ABSTRACT

The present disclosure relates to an electrical energy storage apparatus which forms an interpenetrating, three dimensional structure. The structure may have a first non-planar channel filled with an anode material to form an anode, and a second non-planar channel adjacent the first non-planar channel filled with a cathode material to form a cathode. A third non-planar channel may be formed adjacent the first and second non-planar channels and filled with an electrolyte. The first, second and third channels are formed so as to be interpenetrating and form a spatially dense, three dimensional structure. A first current collector is in communication with the first non-planar channel and forms a first electrode, while a second current collector is in communication with the second non-planar channel and forms a second electrode. A separator layers separates the current collectors.

STATEMENT OF GOVERNMENT RIGHTS

The United States Government has rights in this invention pursuant toContract No. DE-AC52-07NA27344 between the U.S. Department of Energy andLawrence Livermore National Security, LLC, for the operation of LawrenceLivermore National Laboratory.

FIELD

The present disclosure relates to energy storage devices, and moreparticularly to highly penetrating, high surface area, three-dimensionalstructures for electrical energy storage.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

Over the past fifteen years or so, the proliferation of mobileelectronics and electric vehicles has created an increasing demand forhigh-performance batteries that are lighter and store more energy on asingle charge. Most improvements in battery technology have focused onachieving these objectives by developing new and better materials forthe five main components of the battery: anode, cathode, conductivefiller, electrolyte, and (if necessary) the separator. However, theseprevious efforts at improving battery technology have generally focusedmore on the materials used for the battery, but have largely ignoredexploring the geometrical arrangement or internal “shape” or topology ofa battery for the purpose of obtaining improvements in batteryperformance. There is also increasing interest in designing optimalinternal micro or nanoscale structure for a macroscale object shape.

It will also be understood that conventional battery designs aregenerally planar. With a generally planar construction, the anode,separator and cathode of the battery are stacked on top of one another.These layers are then generally packaged in a planar form factor.Alternatively, these layers may be rolled up like a jelly roll andpackaged into a cylindrical form factor.

Researchers have recently manufactured electrodes (i.e., anodes andcathodes) using geometries such as interdigitating combs orinterdigitating posts. However, these efforts have not generallyexplored the possibility of increasing the performance of a battery bytailoring or controlling its physical geometry.

Some efforts have been made with regard to battery architecture,particularly involving designs using gyroid-like structures. U.S. PatentPublication No. 2014/0147747 discusses the construction ofmicrobatteries using porous electrode architectures. U.S. PatentPublication No. 2014/0050988 discusses the use of gyroid structures (notany other minimal or triply periodic surfaces) specifically to form acharge collector. The charge collector is also known as a “currentcollector.” This is the structure used to provide a path for electriccurrent to or from the battery electrodes (anode and cathode).

SUMMARY

In one aspect the present disclosure relates to an electrical energystorage apparatus comprising an interpenetrating, three dimensionalstructure including an electrolyte material, a first non-planar layer ofanode material to form an anode, and a second non-planar layer ofcathode material channel adjacent the first non-planar layer of anodematerial which includes a cathode material to form a cathode. The firstand second non-planar layers may be formed to be interpenetrating. Afirst current collector may be formed so as to be in communication withthe first non-planar layer of anode material, and thus form a firstelectrode. A second current collector may be formed as a secondelectrode in communication with the second non-planar layer of cathodematerial. A separator layer may separate the current collector layers.

In another aspect the present disclosure relates to an electrical energystorage apparatus. The apparatus may comprise an interpenetrating, threedimensional structure formed from an ionically conductive solidelectrolyte material having a plurality of interpenetrating, non-planarchannels. The channels may include a first plurality of channels filledwith an anode material, and a second plurality of channels adjacent thefirst plurality of channels, and interpenetrating the first plurality ofchannels, and being filled with a cathode material. A third plurality ofchannels may be formed adjacent, and interpenetrating, the first andsecond pluralities of channels and may be filled with a material to forma separator. The first, second and third channels may be formed so as toform a spatially dense, three dimensional structure. A first currentcollector is provided in communication with the first plurality ofchannels, and forms a first electrode. A second current collector isformed to act as a second electrode which is in communication with thesecond plurality of channels.

In another aspect the present disclosure relates to a method for formingan electrical energy storage apparatus configured as a threedimensional, periodic structure. The method may comprise forming aninterpenetrating, three dimensional structure having a first non-planarchannel and a second non-planar channel in proximity to the firstnon-planar channel. The first and second non-planar channels may furtherbe interpenetrating. The first non-planar channel may be filled with ananode material to form an anode. The second non-planar channels may befilled with a cathode material to form a cathode. Areas adjacent thefirst and second non-planar channels may be filled with an electrolyte.A first electrode may be formed to operate as a current collector, whichis in electrical contact with portions of the anode material. A secondelectrode may be formed to operate as an electrode, which is inelectrical contact with portions of the cathode material.

In still another aspect the present disclosure relates to a method forforming an electrical energy storage apparatus configured as a threedimensional structure. The method may comprise forming a structure usingan ionically conductive material. First and second non-planar channelsmay be formed in the ionically conductive material in proximity to oneanother, with the first and second non-planar channels further beinginterpenetrating. The first non-planar channels may be filled with ananode material to form an anode. The second non-planar channels may beformed with a cathode material to form a cathode. Areas adjacent thefirst and second non-planar channels may be filled with an electrolyte.A first electrode may be formed to operate as a current collector, whichis in electrical contact with portions of the anode material. A secondelectrode may be formed to operate as a current collector, which is inelectrical contact with portions of the cathode material.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a high level perspective view of a portion of a structureforming a 3D, periodic, energy storage device with interpenetrating wallportions, and where the 3D structure takes the form of a gyroid;

FIG. 2 is a cross sectional view of a portion of one of the materiallayers of the 3D structure of FIG. 1 taken in accordance with sectionline 2-2 in FIG. 1;

FIG. 3 is a highly simplified view of a portion of a 3D solidelectrolyte structure, made with a 3D printing process, havinginterpenetrating channels formed therein which are filled with anode andcathode materials;

FIG. 4 is a simplified illustration of a Schwartz P surface that may beused to construct a 3D energy storage apparatus in accordance with thepresent disclosure;

FIG. 5 is a simplified illustration of a Schwartz D surface that may beused to construct a 3D energy storage apparatus in accordance with thepresent disclosure;

FIG. 6 is a simplified illustration of a Neovius surface that may beused to construct a 3D energy storage apparatus in accordance with thepresent disclosure;

FIG. 7 is a simplified illustration of a N14 Surface that may be used toconstruct a 3D energy storage apparatus in accordance with the presentdisclosure;

FIG. 8 is a simplified illustration of a N26 Surface that may be used toconstruct a 3D energy storage apparatus in accordance with the presentdisclosure;

FIG. 9 is a simplified illustration of a N38 Surface that may be used toconstruct a 3D energy storage apparatus in accordance with the presentdisclosure;

FIG. 10 is a simplified illustration of a Diamond surface that may beused to construct a 3D energy storage apparatus in accordance with thepresent disclosure;

FIG. 11 is a simplified illustration of a Double Diamond surface thatmay be used to construct a 3D energy storage apparatus in accordancewith the present disclosure; and

FIG. 12 is a simplified illustration of a Kagome lattice that may beused to construct a 3D energy storage apparatus in accordance with thepresent disclosure.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses. Itshould be understood that throughout the drawings, correspondingreference numerals indicate like or corresponding parts and features.

The various embodiments of the present disclosure generally relate to aclass of microscale or nanoscale designs for three-dimensional, (“3D”)structures. In one example the 3D structure is an electrical energystorage device, as will be described in detail herein. The 3D structuremay be periodic or aperiodic. It may be ordered or disordered, but animportant feature is that it is interpenetrating and 3D for all of thematerials being used to form the structure. It could be graded densityand feature sizes could change throughout the structure. As will becomemore apparent from the following discussion of a 3D energy storagedevice, as feature size decreases, the surface area increases andtransport distances are reduced.

The 3D architectures disclosed herein are especially well suited forbatteries where the anode, cathode, separator, electrolyte, and/orcurrent collector are patterned into highly interpenetrating butdiscrete phases that have high surface areas and small transportdistances while maximizing the amount of active material (i.e., anode orcathode) that can be packed into a given volume. The various embodimentsdisclosed herein have greater areal, volumetric, or gravimetric powerdensity for a given energy density (or power density) compared toconventional battery designs based on planar layouts such as flatplates, jelly roll layouts, etc., or interdigitated geometries such ascombs and posts. The power density may be limited by mass transport. Theenergy density is given by the nature and the packing density of theactive material. As a result, for a given power load, the architecturesdisclosed herein may be used to manufacture batteries that last longer.

Referring to FIG. 1 there is shown a simplified representation of a 3Denergy storage apparatus 10 (hereinafter simply “3D structure 10”)having interpenetrating layer portions that forms an electrical energystorage device. In this example the structure 10 takes the form of agyroid, although it will be appreciated from the following discussionthat a wide plurality of other 3D structures with interpenetrating wallsor surface portions may be substituted for a gyroid. However, it will beappreciated that the anode, cathode, separator/electrolyte, and currentcollectors may or may not have all the same shape.

The 3D structure 10 of FIG. 1 includes 3D surface wall portions 12 whichare formed relative to one another to be interpenetrating. By“interpenetrating” it is meant that one wall portion 12 cannot bedisengaged from the other by any combination of translations orrotations. That is, in order to separate the two wall portions, whichare not connected, one of the wall portions must be cut. Another exampleof an interpenetrating structure would be two links of a chain.

A small cross-sectional section 14 of just a portion of one of thesurface wall portions 12 is shown in FIG. 2. In FIG. 2, surface wallportion 12 may be formed to include an anode material layer 16, aseparator material layer 18 and a cathode material layer 20. Theinterpenetrating nature of the wall portions 12 can be noted, forexample, at area 22. It should be noted that it is impossible to go fromanode material layer 16 to cathode material layer 20 without penetratingthe separator material layer 18 (FIG. 2).

With further reference to FIG. 1, portions of all of the anode materiallayers 16 may be connected by an electrically conductive material layeror sheet 24. Portions of all of the cathode material layers 20 may beconnected by a separate electrically conductive material layer or sheet26. Material sheets 24 and 26 form current collectors, also sometimesreferred to as electrodes. The material sheets 24 and 26 have portions(not shown) where power connections can be made to some external deviceto allow stored electrical power from the 3D structure 10 to be used topower the external device. It will be understood that no portion ofelectrically conductive material sheet 24 contacts any of the cathodematerial layers 20, and no portion of the material sheet 26 contacts anyportion of the anode material layers 16. These can be separated by asolid separator electrolyte or by a gap or void that is filled withliquid electrolyte. Liquid electrolytes are actually faster due todiffusion. In either event, when an electrolyte is used to fill areas28, this places the electrolyte in contact with all of the anodematerial layers 16 and all of the cathode material layers 20, thusfilling all of the voids within the 3D structure 10.

The 3D surfaces used for patterning may be parametric. For a gyroid, forinstance, boundaries of three-dimensional gyroid structures can bedefined by the equations:sin(2*pi*x/L)*cos(2*pi*y/L)+sin(2*pi*y/L)*cos(2*pi*z/L)+sin(2*pi*z/L)*cos(2*pi*x/L)=+t/2andsin(2*pi*x/L)*cos(2*pi*y/L)+sin(2*pi*y/L)*cos(2*pi*z/L)+sin(2*pi*z/L)*cos(2*pi*x/L)=−t/2  [6],so that the thickness of the gyroid is the parameter “t” and its period(i.e., the length of a unit cell) is “L”.

Controlling the thickness of the surface wall portions 12 tunes iontransport properties so that active material is depleted from the anodematerial layer 16 evenly. Consequently, for different active materials,the thickness of the surface(s) used in the design may change. Ingeneral, thinner is better. Ideally, the active materials should have ananoscale thickness.

It is also expected that manufacturability constraints are likely toalso place constraints on the thickness of the surface, as well as itsunit cell length.

A 3D electrical energy storage structure such as 3D structure 10 in FIG.1 may be manufactured using present day 3D printing or 3D fabricationprocesses. If manufactured using a well known 3D printing process, thenthe 3D structure 10 will be manufactured as a series of discrete layerssuccessively formed one on top of another. In this fashion the channelsnecessary to form the anode layer, the cathode layer, and any othermaterial layers (e.g., separator layer) would be formed substantiallysimultaneously as each layer is printed when the different types ofmaterial are deposited by different print heads of a 3D printing system.

FIG. 3 shows one high level example of how the charge collectors may bemay be formed with an interpenetrating construction. In this example thewall portion 12′ has charge collectors 24′ and 26′ disposed ininterpenetrating fashion on opposite surfaces of the separator layer 18.Charge collector 24′ is disposed in interpenetrating fashion with anodematerial layer 16 and charge collector 26′ is disposed ininterpenetrating fashion with cathode material layer 20. Such aconstruction minimizes electrical transport distances to the chargecollector layers 24′ and 26′.

In one example, the 3D structure 10 may be comprised of an ionicallyconductive solid electrolyte using, for example, projectionmicrostereolithography. The electrically conductive solid electrolytehas discrete, interpenetrating channels formed in it during the 3Dprinting process. The channels may be linear, but it will be appreciatedthat the channels will be non-linear for a 3D gyroid structure or mostother 3D periodic or aperiodic structures. All the materials could bedirectly printed, and it is expected that this is likely to be apreferred implementation.

Subsequently, each of the channels 32 and 34 may be in-filled withactive materials. For example, anode material may be filled into channel32 and cathode material may be filled into channel 34. Each of theactive materials preferably has some conductive filler loaded into itbefore it is deposited in its respective channel 32 or 34 to improve theelectrical conductivity of its associated anode or cathode material.Such conductive filler material may be Graphene, carbon nanotubes(CNTs), copper particles or wires, aluminum particles or wires, orcarbon black. Again, a principal objective is to create a nonplanarcurrent collector that is continuous and creates short electronictransport distances. Next, each anode and cathode material has portionsthereof attached to a respective current collector using a conductiveepoxy, such as was described in connection with material sheets 24 and26 (i.e., current collectors) in FIG. 1. An additional channel,represented by dashed line 36, may be formed in the solid electrolyte 30for the separator as well. The completed structure forms a battery whichcan then be tested. Ultimately, it is expected to be advantageous, froma manufacturing/cost standpoint, to directly pattern all of the currentcollector, active materials, conductive fillers, andseparator/electrolyte directly with a 3D fabrication process.

Aside from tuning parameters in the 3D structures used in the design,these designs can be used with any combination of anode, cathode,electrolyte, separator, and current collector materials that arenormally used in conventional battery designs. These 3D energy storagestructures of the present disclosure are expected to be useful in bothprimary and secondary batteries, and could be applied in theconstruction of batteries for use in any application where power orenergy density is a concern, either in terms of battery lifetime orenergy storage capability on a single charge. Single charge storagecapability is especially important for batteries used with mobiledevices such as smartphones, tablets, laptops, MP3 players, gamingdevices, GPS units, portable radios, power tools, home energy storagedevices, grid storage devices or systems, or portable water purificationunits, just to name a few potential applications. The teachings providedherein are also expected to be important in helping to make batterieslighter for a given storage capacity, as compared to conventionalbattery designs. Minimizing the weight of the battery for a given levelof power density is also expected to be especially important withapplications involving many of the above listed devices, as well as withapplications involving battery powered automotive vehicles, batterybackup systems for use on aircraft, or even remotely controlled drones.

The present disclosure, in certain embodiments, makes use of geometriesderived from triply periodic structures such as gyroids and Schwarzminimal surfaces, or other interpenetrating 3D structures, to achieve asignificant improvement in power density over the previous conventionalgeometries at the same energy density and comparable feature (i.e.,material thickness) sizes. A small number of examples of various typesof periodic, 3D structures which may be used to form the 3D structure 10are illustrated in FIGS. 4-12, which show a Schwartz P surface (FIG. 4),a Schwartz D surface (FIG. 5), a Neovius surface (FIG. 6), a N14 Surface(FIG. 7), a N26 Surface (FIG. 8), a N38 Surface (FIG. 9), a Diamondsurface (FIG. 10), a Double Diamond surface (FIG. 11), and a Kagomelattice (FIG. 12). The present disclosure may make use of any of theforegoing surfaces discussed herein or virtually any other surfaceprovided at the following link:

-   -   http:www.susqu.edu/brake/evolver/examples/periodic/periodic.html.

The precise surface configuration could also be derived using shape ortopology optimization to yield many different structures.

The various designs proposed in the present disclosure can be combinedwith improved battery materials to yield even further gains in batteryperformance over conventional designs using existing materials. It isexpected that changes in material properties will affect the parametersdetermining the size and shape of the surfaces, but will not affectsubstantially the performance improvements obtained by usinginterpenetrating, periodic, 3D designs instead of conventionalplanar-based battery designs. It will be appreciated thatinterpenetration is a key feature, and it is desirable to maximizesurface area without sacrificing active material.

The architectures of the present disclosure are expected to haveparticular utility with applications requiring portable power sourcessuch as mobile phones, computing tablets and other portable electronicdevices. The embodiments disclosed herein are also able to be chargedmore rapidly for a given level of energy than conventional batteries.The designs and teachings described herein may account for differentcapacities of the active materials. The designs and configurationsdiscussed herein may also have different sizes and shape and amounts ofactive materials to boost overall battery capacity and efficiency.

The 3D energy storage architectures disclosed herein can also yieldlighter or smaller batteries for a given quantity of energy storage, ascompared to conventional planar or jelly roll layouts. This makes thevarious embodiments of the present disclosure especially valuable whereweight is an important concern, such as with electronic devices used inmilitary applications or with remotely controlled, battery powered landand air vehicles such as drones.

While various embodiments have been described, those skilled in the artwill recognize modifications or variations which might be made withoutdeparting from the present disclosure. The examples illustrate thevarious embodiments and are not intended to limit the presentdisclosure. Therefore, the description and claims should be interpretedliberally with only such limitation as is necessary in view of thepertinent prior art.

What is claimed is:
 1. An electrical energy storage apparatus, comprising: an interpenetrating, three dimensional, triply periodic structure including: an electrolyte material; a first non-planar layer of anode material to form an anode; a second non-planar layer of cathode material which conforms to a contour of the first non-planar layer of anode material, and which forms a cathode; the first non-planar layer and the second non-planar layer being formed so as to be interpenetrating in a triply periodic configuration, and which form a plurality of wall portions, and where the wall portions form non-parallel channels throughout the interpenetrating, three dimensional, triply periodic structure; a first current collector layer in communication with the first non-planar layer and forming a first electrode; a second current collector layer in communication with the second non-planar layer and forming a second electrode; and a third non-planar layer forming a separator material disposed between the first non-planar layer and the second non-planar layer, and following the contour of the first non-planar layer and the second non-planar layer, with the first non-planar layer, the second non-planar layer and the third non-planar layer forming integrated wall portions propagating in the interpenetrating, three dimensional, triply periodic structure; wherein the integrated wall portions forming the interpenetrating, three dimensional, triply periodic structure repeat periodically and uniformly in a plurality of differing non-parallel directions to provide channels extending in uniform, repeating patterns in the plurality of differing non-parallel directions, and wherein the integrated wall portions form uniform thicknesses; and wherein each of the first and second non-planar layers of material forming the anode and cathode, respectively, are exposed on opposing sides of the integrated wall portions throughout an interior of the structure.
 2. The apparatus of claim 1, wherein the first current collector layer is non-planar.
 3. The apparatus of claim 1, wherein the second current collector layer is formed adjacent the second non-planar layer of cathode material.
 4. The apparatus of claim 1, wherein the first non-planar layer of anode material includes an electrically conductive filler material to improve electrical conductivity.
 5. The apparatus of claim 1, wherein the second non-planar layer of cathode material includes an electrically conductive filler material to improve electrical conductivity.
 6. The apparatus of claim 1, wherein the apparatus forms a battery.
 7. The apparatus of claim 1, wherein the interpenetrating, three dimensional, triply periodic structure comprises one of: a gyroid; a double gyroid; a Schwartz surface; kelvin foam; an octet truss; a kagome lattice; a Neovius surface; an N14 Surface; an N26 Surface; an N38 Surface; a Diamond surface; and a Double Diamond surface.
 8. The apparatus of claim 1, wherein the integrated wall portions provide a uniform, undulating, interpenetrating curvature throughout X, Y and Z dimensions of the structure. 